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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 19-34 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is demonstrated that dicarboxylic acids of uniform lengths, obtained by degrading chain-folded polyethylene single crystals, can be converted to paraffins via the intermediate diiodide by means of the procedure of Barton et al. Thus we are now in the position of obtaining uniform paraffins of chain lengths longer than hitherto available for the study of the crystallization of oligomeric chains. Measurements of melting points and heats of fusion revealed major differences between the paraffins and the corresponding parent dicarboxylic acids. It follows that such measurements on the unmodified products of the nitric acid degradation cannot be used directly for the assessment of the chain traverse length and the degree of crystallinity. It was found further, that the intermediate diiodide is a sufficiently close approximation to the paraffin for the purposes just quoted.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1227-1233 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method is proposed for use of the universal calibration curve, i.e., the product of molecular weight and intrinsic viscosity versus retention volume, in calculating the molecular weight distribution of a polymer from gel-permeation chromatography (GPC) when the Mark-Houwink relation of the polymer in the solvent used for the GPC is unknown. This is achieved by measuring the viscosity of each fraction with an automatic capillary tube viscometer. Application of this technique to poly(vinyl chloride) and poly(vinyl acetate) proved to be successful.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1235-1237 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1491-1502 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of optical rotation of the environment is calculated for the Hv and Vv low-angle light-scattering patterns of two-dimensional spherulites. As with the effect or birefringence, the change in the Hv pattern is greater than that of the Vv pattern. With increasing optical rotation, the patterns lose their characteristic shape and become more circular.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1521-1543 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The processes associated with the deformation and fracture of polystyrene tested in uniaxial tension have been studied over a range of strain rates from 1.4 × 10-2 to 4.3 × 10-7 sec-1 and at constant stresses between 4.1 and 2.9 kg/mm2. The effect of strain rate on the surface craze distribution prior to fracture, the fracture stress, the mechanism of nucleation of cracks, and the nature of fracture surfaces associated with slow and fast crack propagation have been determined. The changes in fracture surface appearance have been studied using optical and stereoscan microscopy. The observations are consistent with the model presented in a previous paper. Fracture is preceded by craze formation, cavitation in the craze, coalescence of cavities to form large planar cavities which propagate slowly until a critical stage is reached at which fast crack propagation occurs. The effect of changes of strain rate and material variables on these processes is discussed.
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  • 6
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polypropylene film was biaxially stretched in one step in air at 140°C or 152°C, and the deformation was studied optically. A linear relation held between Δnss and vA-½ for vA 〉 10, at both temperatures, where Δnss is the birefringence with respect to the normal to the film and vA is the degree of stretching expressed as the factor by which the area of the film is increased. Extrapolation of data in this linear region yielded a value of 20 × 10-3 for -Δnss at infinite vA. Since it is presumed that the polypropylene molecules lie completely parallel to the film surface when the film is stretched infinitely, -Δnss at vA-½ = 0 must be just half Δn°, the intrinsic birefringence in the case of completely parallel orientation. Thus, Δn° must be 40 × 10-3. This value was obtained experimentally in uniaxial stretching when the birefringence with respect to the direction of drawing was extrapolated to infinite extension. Similar relations held between np, the average of the refractive indices in the two stretching directions, and vA, and between nss, the index normal to the film, and vA. By similar extrapolations, (1/2)(n′γ + n′β) and n′β = n*α′ were estimated, and thence nα′ was obtained. Here, n′α and n′β are the refractive indices along the c axis (molecular chain axis) and b axis. All these optical parameters refer to a density of 0.900 g/cm3. Hence by applying a density correction to those values, the principal refractive indices and the intrinsic birefringence of polypropylene crystal were evaluated as follows: nα = 1.5522, nβ = n*α = 1.5106 and Δnc° = 4.16 × 10-3, where n*α is the refractive index prependicular to the b and c axes of the crystal.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1617-1626 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The swelling curves of 6μ films of low conversion homopolymers and copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) were obtained in water by an optical microscope technique. Poly(AM) swelled appreciably faster than poly(NIPAM) but there was no apparent correlation between overall swelling rate and copolymer composition. A 57/43 (mole %) AM-NIPAM copolymer swelled fastest. Sequence distribution calculations indicated that its backbone structure tended toward comonomer alternation, which might reduce the extent of hydrogen bonding in the film. The amount of water sorbed during swelling, as approximated from increasing film thickness, was proportional to the square root of time and agreed well with previous work in the literature. Homopolymer films from runs of ca. 50% conversion consistently swelled slower than their low conversion counterparts, probably due to branching and increased entanglements. Heating also promoted slower film swelling due to a tightening of the film structure and/or a low degree of imidization. Monomer reactivity ratios and Alfrey-Price Q and e values for NIPAM were calculated. Cloud points of 5% aqueous solutions of the copolymers were measured and found to decrease with increasing NIPAM content.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1637-1637 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 689-703 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reduced specific viscosity of poly(methacrylic acid) has been studied in ethanol-0.002N HCI solvent mixtures as a function of polymer concentration, alcohol concentration, and temperature. In addition, experiments were performed at different HCI concentrations and with KCI instead of HCI. Both intrinsic viscosity and Huggins coefficient were shown to undergo unusually strong variations. Two minima and two maxima could be demonstrated in intrinsic viscosity. The Huggins coefficient seems to show corresponding variations. The first minimum in intrinsic viscosity indicates that the coil volume has collapsed almost to an Einstein sphere. In this region the Huggins coefficient is extremely large (of order 102) and is controlled by coil association. It was shown that several forms of intramolecular interaction must be assumed to be competing to account for this behavior. The presence of HCI, particularly in the preponderantly aqueous phase, is required to suppress the polyelectrolyte effect. It is found, however, that the behavior of the solutions at relatively high ethanol concentrations is more sensitive to HCI content than is that of highly aqueous solutions. KCI can be used to replace HCI over most of the range. Increase in temperature shifts the turning points of the curves to lower alcohol concentrations. Some evidence has been found that the association constant giving rise to dimers increase with rate of shear. The importance of poly(methacrylic acid) as a chemically simple model substance for various biopolymer effects is stressed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1773-1786 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature dependence of the crystallinity of bulk polyethylene is calculated in terms of branching (methyl or ethyl side groups on the chain). In the model, the chains are approximately parallel and they pass through alternating amorphous and crystalline layers forming a periodic structure. The crystalinity and the thicknesses of the layers are determined by minimization of the free energy. The theory shows that the temperature at which the polymer begins to crystallize is lower than the melting point of pure polyethylene and that the thicknesses of the layers becomes smaller as the temperature decreases.
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  • 11
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1841-1844 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1845-1845 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 13
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1865-1877 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Drawing of mats of linear polyethylene single crystals prepared from dilute solution is possible at temperatures above about 90°C. The structure and properties of the drawn specimens are much different from those ordinary drawn bulk polymer. Drawn mats have been investigated by differential scanning calorimetry. The characteristic experimental results are: (a) a broad melting curve, (b) considerable superheating depending on the rate of heating, (c) constancy of the melting point and the heat of fusion with annealing, (d) deviation from the relation between the heat of fusion and the density obtained for the drawn bulk specimens, (e) appearance of two melting peaks in samples annealed at temperatures above about 130°C. These results imply that the structure of the drawn mat is characterized by a larger number of the tie chains connecting the neighboring crystals (the structure postulated in earlier papers) than is the case in ordinary drawn bulk polymer. It can be concluded that the transformation of a fringed micellar type of structure to the folded lamellar structure may be difficult during annealing unless crystals melt and then recrystallize during cooling.
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  • 14
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the NMR second moment of a uniaxially oriented sample of polyethylene single crystals in the range of temperatures from -196°C to 130°C and its dependence on the alignment angle γ between the orientation axis (preferential direction of the molecular chains) and the NMR magnetic field are presented. The experimental results are discussed mainly with respect to the high temperature relaxation, called the α process, in polyethylene. They are compared to theoretical predictions made for a number of mechanisms of molecular motion in Part I of this work. Only one of the mechanisms considered is found to be in quantitative agreement with experiment, the mechanism here referred to as flip-flop motion. This consists of thermally activated rotational jumps of the crystalline chain segment between folds around its axis between two equilibrium sites in the lattice. Each rotational jump through 180° is accompanied by a shift of the molecule along its axis by one CH2 group. The discussion of the low-temperature relaxation of polyethylene, the γ process, is based partly on the above measurements and partly on measurements of second moments for unoriented polyethylene samples varying widely in morphology and noncrystalline content. The decrease of the second moment observed with these samples between -196°C and 20°C is taken as a measure of the intensity of the γ process. A linear correlation is found between the decrease in the second moment, designated ΔS, and the noncrystalline content, 1 - αm; this can be represented by ΔS = 1.4 + 22.1(1 - αm). It is shown that neither the crankshaft mechanism not the kink mechanism is able to account quantitatively for this result. The model of a chain end moving in a vacancy fails to adequately describe the angle dependence of ΔS in oriented polyethylene single crystals. The “sandwich model” of a polyethylene single crystal, in which the crystalline core is covered by noncrystalline surface layers, is in better agreement with observations.
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  • 15
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 705-712 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intrinsic viscosity of poly(methacrylic acid) has been studied in mixtures of 0.002N HCI and a series of aliphatic alcohols. The behavior found previously with ethanol is shown to apply in the case of admixture with methanol, n-propanol, and 1,2-ethanediol. The intrinsic viscosity first drops to a minimum and then increases sharply to a maximum. With ethanol and n-propanol the maximum is followed by another minimum and maximum. With methanol and 1,2-ethanediol this effect is absent or much smaller. Methanol and 1,2-ethanediol are equivalent, molecule for molecule, in their influence on the intrinsic viscosity. With ethanol and n-propanol there are in addition one and two shoulders, respectively, in the passage from the first minimum to the first maximum. Good correlation of the data is obtained if alcohol concentration is plotted as the mole fraction of carbon atoms per OH group (in the alcohol). The first maximum in particular was shown to correspond to the point where the number of water molecules per alcohol in the solvent mixture equals the number of C atoms per hydroxyl in the alcohol. The shoulders and first minima were found to correspond to other simple ratios. This behavior reflects changes in alcohol-water structure. The maximum in the case of ethanol was found to be the most pronounced and ethanol seems to possess optimal properties from this point of view.
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  • 16
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 727-738 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric relaxation data have been obtained for two ethylene-methacrylic acid copolymers (containing about 4 mole-% methacrylic acid units and about 8 mole-% methacrylic acid units, respectively) and the lithium, sodium, and calcium salts prepared by partial neutralization of the polyacids. The frequency range employed was from 50 Hz to 10 kHz and the temperature range was from -130°C to 100°C. Attention is focused on three dielectric loss regions labeled β, β and α in order of increasing temperature. The β′ process (-10°C at 100 Hz in the salts only) correlates with a mechanical loss process previously reported and is attributed to microbrownian motion taking place in an amorphous hydrocarbon phase. The β′ process (20°C at 100 Hz) has also been observed mechanically and is attributed to the same mechanism as the β process. The higher temperature of this relaxation compared to the β relaxation is attributed to the presence of acid groups which form crosslinks composed of interchain hydrogen bonds. The α process (〉50°C at 100 Hz in the salts only) correlates with dielectric and NMR data previously reported for a sodium salt and is assigned to motions within ionic domains formed by the clustering of salt groups.
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  • 17
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    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 799-806 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The tensile stress relaxation master curve for polyvinylcyclohexane (completely hydrogenated polystyrene) has been measured. Direct relaxation experiments were carried out at several temperatures above the glass transition temperature over the rather long time range of four orders of magnitude. This long time span was realized by calculating the modulus during the period when a constant small strain rate was applied to the sample as well as during the usual constant strain interval. A computer solution to the Boltzmann superposition equation allowed data from these two regions to be joined into a smooth curve representing E(t), a parameter indicative of an instantaneous strain experiment. The measured Ti was found to be 143°C; Tg is expected to fall within several degrees of this temperature. This result is apparently at odds with a previously reported Tg value of 120°C. More importantly, the maximum value of the negative slope of the stress relaxation master curve of polyvinylcyclohexane in the primary transition region was only slightly different from that for polystyrene. This observation clearly indicates that the molecular factors which result in the highly coupled nature of the primary transition in polystyrene are not strongly dependent upon any side-chain π-π interactions which might be present in polystyrene.
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  • 18
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    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 807-811 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
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  • 19
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    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 833-839 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A chromatographic technique is described where the stationary phase is a layer of a very high molecular polystyrene fraction (M = 107) on glass beads (ballotines). The mobile phase is cyclohexane passing the column at a constant temperature below the theta-temperature. A polystyrene sample of sufficiently low molecular weight (M ≤ 106) injected as a small plug at the top of the column is fractionated because the distribution between the mobile and the stationary phase depends on the molecular weight. Since the large molecules preferentially remain in the stationary phase, the smaller molecules leave the column first. The fractionation effect is inverse to that found in GPC experiments. The separation efficiency is rather good and can be described by a simple thermodynamic theory.
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  • 20
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sedimentation equilibrium in the ultracentrifuge means that there is such a distribution of molecular species throughout the cell, that the centrifugal forces are balanced by differences in the activities. This provides a method for determination of the activities and the chemical potentials in polymer solutions which, in principle, is very simple and reliable. A complication is caused by polydispersity of the dissolved polymer. If one assumes that the interaction parameter depends on concentration and temperature, but not on molecular weight, it is possible to determine the chemical potential of polymer and solvent from the ultracentrifugal data. Experiments have been carried out on the systems polystyrene-toluene and polystyrene-cyclohexane at different temperatures and in the concentration range 0-80 wt-%. The results are expressed in the data for the chemical potential of the solvent, the number average chemical potential of the polymer and the interaction parameter χ.
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  • 21
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2095-2103 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electron-microscopic texture and physical properties of a styrene-butadiene-styrene (SBS) block copolymer obtained by casting from toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone are discussed. Two peaks are observed in the mechanical loss (tan delta;) curve at -70 and 100°C which are attributed to segmental motion of polybutadiene and polystyrene, respectively. The polybutadiene peak heights are in the order of solubility in the solvent used; the polystyrene peak heights are in converse order. In addition to these peaks, a third peak is observed at 10°C for specimens cast from ethyl acetate or methyl ethyl ketone. A transition corresponding to this peak is also noticed in thermal analysis. It is proposed that aggregation of styrene blocks is relatively incomplete in specimens cast from solution in poor solvents.
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  • 22
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2153-2161 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization of elemental selenium has been studied in light of present concepts of crystallization in organic polymers. Bulk-crystallization kinetic data as measured by a dynamic density technique and spherulite growth-rate data as measured by optical microscopy are presented for the temperature range 70°C to 160°C. Plots of extent of isothermal crystallization versus time were sigmoidal in shape. Spherulite growth rates were constant for a given temperature and reached a maximum at approximately 130°C. Evidence is presented for secondary crystallization in selenium, and a model is proposed for destruction of chain folds with interlamellar crystallization during the spherulitic-to-“metallic” transformation above 100°C.
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  • 23
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1413-1414 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 24
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 105-126 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The melt rheological properties of both linear and branched polyethylene were investigated by use of narrow molecular weight distribution fractions and experimentally polymerized samples. Studies carried out in steady shear and in oscillatory shear yielded information concerning both the melt viscosity and the melt elasticity as a function of molecular structure, where the latter was characterized by various solution property techniques. The 3.4-3.5 power dependence of the low shear limiting viscosity on molecular weight was confirmed for linear polyethylene. The effect of long-chain branching on rheological properties was defined both at constant molecular weight and at constant molecular weight distribution and coupled with variation of molecular weight.
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  • 25
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 148-152 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 26
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 127-141 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The investigation of the effect of molecular structural variables on the melt viscosity of polyethylene was extended to the shear dependent region by application of a reduced variables treatment following, in a formal sense, that of Bueche. Viscosity-shear rate data were obtained for a series of experimentally polymerized linear polyethylene samples having a range of molecular weights and molecular weight distributions as characterized primarily by gel permeation chromatography. These data could be superimposed on a single reduced variables flow curve using parameters which were a function only of temperature, limiting Newtonian viscosity, M̄w, and M̄w/M̄n. The same treatment was successfully applied also to branched (low-density) fraction data discussed in a previous paper, with additional correction for long-chain branching. However, different reduced variables curves were obtained for the branched and linear cases.
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  • 27
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 153-159 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 28
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 161-165 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 29
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 167-172 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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  • 30
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 173-174 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 31
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 174-175 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 32
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 207-224 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A discussion is given of the behavior of a mathematical model chosen to approximate conditions during precipitation chromatographic fractionation of polymer (Baker Williams fractionation). With only one molecular weight species of polymer a complete solution of the mathematical model was obtained. With more than one species it was necessary to use a computer solution. Curves showing the movement of polymer containing one and two species of polymer are given for a variety of conditions of operation. It was found that the degree of fractionation of polymer approaches a limiting value with increasing length of column. Under some conditions the degree of fractionation may go through a maximum with length of column. The equilibrating distance (distance of travel of the liquid phase required to establish equilibrium of polymer between the liquid and the bed) was found to be very important in determining the fractionation.
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  • 33
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 177-190 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational properties of optically active macromolecules are considered. A statistical zigzag model is used for the calculation of averaged physical properties. The macromolecule is considered to consist of segments of two different types with a statistical distribution of lengths. The expressions for the mean square of the end-to-end vector h2 and the dipole moment μ2 and also of the mean optical anisotropy ΔA and the anisotropy of the optical rotation tensor ΔG were obtained in the cases of freely jointed and freely rotating segments. The equations obtained were applied to the problem of the helix-coil transition. In the case of poly-α-olefins the values of h2, μ2, and ΔA, are larger than corresponding values for typical optically inactive macromolecules. The anisotropies ΔA and ΔG of two poly-α-olefins of similar structures were calculated. The polarizability theory of optical activity was used for the calculations of ΔG. The values obtained for ΔA are similar, but the values of ΔG differ markedly. The possibility of obtaining valuable information about the structure of optically active macromolecules in solution by a study of anisotropy of the optical rotation tensor is considered.
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  • 34
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 191-205 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements have been made on a series of linear atactic polystyrenes whose molecular weights range from 900 to 1.8 × 106, where Mw/Mn ≪ 1.2. Spin lattice relaxation times have been measured in the laboratory frame (T1) and in the rotating frame (T1ρ) in the temperature range 90-500°K. Two major relaxation minima were observed in both sets of measurements. The high temperature process corresponds to the glass transition (α process), the position of the minimum depending on the chain length. The low temperature process appears to originate from the n-butyl endgroups in the polymer, its position being independent of chain length while its intensity is inversely proportional to molecular weight. No other minima were observed, in contrast to some other observations made by broadline and pulsed NMR techniques. Relaxation was exponential in all cases except in the region of the high temperature T1ρ minimum and above. This nonexponential behavior is possibly connected with the transition at T 〉 Tg observed by a number of other techniques and which is thought to correspond to a transition between two types of liquid state. A correlation frequency diagram has been drawn for all the processes observed in polystyrene by other techniques, (α, β, αβ, γ, and δ) which shows that the T1 and T1ρ minimum positions correlate well with the α process and that there is a possible contribution to the relaxation due to the γ process on the low temperature side of the α process. At these measurement frequencies the α and β processes are merged into an αβ process. There is no evidence for a contribution from the mechanical δ process. The effect of the endgroups is observed to very high molecular weights (4.98 × 105), and it seems that a three-dimensional diffusion model would be more adequate than the one-dimensional model used to interpret similar behavior of paraffins and polyethylenes. Measurements of T1 in the low-temperature region would constitute a method for a rough measurement of the molecular weight of these polymers.
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  • 35
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 225-242 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Calorimetric and dilatometric studies have been made of the fusion process of linear polyethylene crystals precipitated by high speed stirring from solution. It is shown that long-time annealing at elevated temperatures alleviates the superheating observed when rapid heating rates are employed. By the annealing procedures that have been adopted, a small but demonstrable fraction of high melting material can be produced whose melting temperature depends on the crystallization temperature. For crystallization at 105°C, followed by annealing at 142°C, a melting temperature of 146.0 ± 0.5°C is observed. The dissolution temperature in xylene, determined for the same sample, is consistent with the high melting temperature observed for the pure polymer. It is recognized that a state of high axial orientation need not necessarily be identified with extended chain crystals. Consequently, the increased melting temperature can result from either an increase in the crystallite size or a reduced interfacial free energy relative to crystallites produced by the more conventional mode of crystallization.
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  • 36
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 277-287 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Studies have been made on the dynamic and steady-shear melt rheology of an ethylene-methacrylic acid copolymer and two of its salts obtained by partial neutralization with sodium and with calcium bases. Measurements were made with a Weissenberg rheogoniometer over a broad range of shear rates and frequency in the temperature interval mainly from 100 to 160°C. The temperature coefficients of dynamic and steady shear viscosity are evaluated at both constant shear rate and constant stress. Likewise, complex dynamic viscosities and apparent high steady-flow viscosities and intercompared at equivalent frequencies and shear rates. The un-ionized acid copolymer shows good correlation between the frequency dependence of the complex viscosity and the shear rate dependence of the apparent viscosity. This is not true for either the sodium salt or the calcium salt. These results are consistent with the two-phase structural model for these materials, i.e., a matrix of hydrocarbon in which are embedded ionic domains.
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  • 37
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 243-276 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An x-ray diffraction method for the simultaneous determination of crystallinity (including intracrystalline defects), effective Debye-Waller factors, and atomic positions has been developed and applied to semicrystalline polyethylene. It was found that this material unambiguously constitutes a two-phase system. Measurements of intracrystalline lattice disorder in the chain direction and perpendicular to the chain direction show these to be in the ratio 1:2.5. Lattice disorder was principally of the first kind. Paracrystalline disorder in the [110] direction was less than 2.4% at all experimental conditions. Results include measurements of degree of crystallinity, particle size, space group, and unit cell parameters and variation of these quantities with crystallization temperature, ambient temperature, and time.
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  • 38
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1955-1969 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Equations are developed for describing the effect of interspherulitic interference on the scattering of light by anisotropic spherulites. These are used to account for the variation in VV and HH scattered intensity during the course of spherulitic crystallization. The scattering depends upon the number of spherulites, their size, their anisotropy, the difference between one of their polarizabilities and that of the surroundings, and the radial distribution function of spherulite centers.
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  • 39
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1971-1985 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isotactic 3-methylbutene homopolymers and copolymers (of low 1-olefin content) exhibit a major transition between 50 and 100°C, which dilatometric, density, and NMR observations indicate is not a glass transition, but rather a crystal-crystal transition occurring within the crystalline phase, the only phase present in significant amount. Fibers prepared from these polymers show a very high degree of orientation and crystallinity, have measured densities close to the theoretical crystal densities, and exhibit abrasion debris and electron microscopic evidence of crystalline lamellae. The fibers have a quasistatic initial modulus equivalent to the sonic modulus and exhibit very low stress relaxation and very high elastic recovery from large extensions. The fact that the fiber is highly crystalline and fully oriented, with a comparatively low initial modulus, high elastic recovery, and an extensibility of about 40%, indicate that the crystalline lamellae themselves, joined together in stacks, are able to deform (probably bend) elastically, and that the aggregate is able to undergo large elastic deformations.
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  • 40
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 333-353 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosities, rubbery deformations, densities, and their dependence on temperature have been measured for several series of polybutadienes with molecular weights ranging from 5,000 to 400,000 and differing in proportions of cis and trans structures (cis content from 40 to 95%). On the basis of the viscosity measurements the critical molecular weight Mc has been determined, corresponding to a sharp change in the nature of the viscosity versus molecular weight dependence. Rubbery deformations are displayed pronouncedly in specimens with M 〉 Mc and are closely related to the appearance of non-Newtonian flow. The value of Mc depends on the relative content of cis and trans forms. When M 〉 Mc, the initial viscosity is a parameter sensitive to the microstructure of polybutadienes, so that with at a single molecular weight, depending on the ratio of cis and trans units, the viscosity may vary over a more than tenfold range. The glass transition temperature and activation energy of viscous flow rise regularly with increasing trans content in the polymer chain, these parameters becoming independent of the molecular weight for specimens with M 〉 Mc within a series of polybutadienes of equal microtacticity. Thermomechanical investigations of polybutadienes also made it possible to define more accurately the boundaries of the crystallization region and the dependence of the melting point on the microtacticity. The results obtained are discussed on the basis of modern ideas of polymer structure.
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  • 41
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 371-381 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Normal stress and shear stress of concentrated polystyrene solutions in a chlorinated diphenyl were measured under steady flow and oscillatory shear flow in a Weissenberg rheogoniometer. The normal stress difference was observed to oscillate at double the frequency of the applied shear strain with amplitude proportional to the square of the applied amplitude, while the shear stress was found to oscillate at the same frequency with amplitude proportional to the applied amplitude. A theoretical relation between the displacement of the oscillatory normal stress difference from zero level and the dynamic modulus derived by Lodge and other investigators was confirmed experimentally, and the theoretical predictions of Coleman and Markovitz concerning the relation among steady-flow normal stress difference and dynamic modulus were also confirmed. However, the theoretical predictions of Lodge, of Spriggs, Huppler and Bird, and of Williams on the relation between the amplitude and phase of oscillatory normal stress and those of oscillatory shear stress did not agree with experimental results.
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  • 42
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 541-554 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dilute solution parameters were determined for polymethylphenylsiloxamer fractions (5 × 104 〈 M 〈 1.5 × 106) in toluene, cyclohexane, and diisobutylamine (θ ≈ 30.4°C). The data are interpreted by the procedure suggested by Flory and Fox. Minor deviations from theory are noted. Polymers from both cis- and trans-cyclotrisiloxanes were investigated. The major portion of the work, however, was concentrated on fractions derived from the trans form. From the data obtained, a characteristic ratio of dimensions (r02/rof2)½ of 1.56 was determined. The hydrodynamic parameter Φ was determined to be (2.0 ± 0.3) × 1021. The appropriate model for the polymer is indicated to be the impermeable random coil with slight hindrance to rotation about backbone skeletal bonds.
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  • 43
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 583-594 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic markings of concentric bands are formed on the fracture surface of tensile specimens under certain loading conditions. The marking form in the fast crack growth region of the mirror area of fracture. Optical and electron optical microscope techniques have been used to study the morphology of the markings. It is shown that in this region the crack propagates along the interface between the craze, in which the crack nucleated, and the bulk material. The mackerel pattern is caused by the crack jumping from one craze-matrix interface to the other.
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  • 44
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 605-624 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Incorporation of plasticizers or other inert, liquid diluents causes a profound weakening of rubbers. The modulus of elasticity and tensile strength decrease approximately with the square of the gel fraction v0 of rubber which was present at the time of formation of the three-dimensional network. Equlibrium swelling of plasticized rubbers is well represented by v2m = kv0, where v2m is the volume fraction of rubber network in the swollen state, at equlibrium, and k a constant equal to v2m for the unplasticized rubber. This swelling law is independent of the way in which v0 is obtained; inert liquid diluents, comprising molecularly dispersed compounds, as well as suspensions of insoluble liquids, gases, and chemically inert, solid fillers yield the same relation. Further, it is independent of the chemical nature of solvent and rubber. It appears that also the mechanical properties of foams, liquid-filled foams, and plasticized elastomers containing the same volume fraction of network rubber are very similar.
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  • 45
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 649-652 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 46
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 679-687 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermodynamic functions of ten monomeric compounds have been calculated for three temperatures by the statistical method using molecular structural data and vibrational assignments. The ideal gas state entropies at 298.15°K are: maleic anhydride, 71.9; β-propiolactone, 69.1; vinylene carbonate, 70.1; cyclopentadiene, 65.3; diketene, 72.3; cyclopropene, 58.7, vinyl fluoride, 60.4; ethyleneimine, 62.8; butatriene, 71.7; and carbon suboxide, 66.0 cal./deg-mole. The standard free energies and equilibrium constants of formation are also derived by using mostly the published data on the heats of formation of these monomers.
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  • 47
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 713-726 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(methacrylic acid) has been studied in 0.002N HCl-ethanol mixtures as a function of molecular weight. A different dependence on molecular weight is noted at different alcohol concentrations. Since the intrinsic viscosity passes through a series of extrema with changes in alcohol concentration, the dependence on molecular weight has been considered in two regions of alcohol concentration in particular. The region of the first minimum and the region of the second minimum (or overall maximum). In the region of the first minimum, intrinsic viscosity is proportional to M½, just as in 0.002N HCl. The Huggins coefficient k′ is large (ca. 60) but drops to about 10 when the molecular weight exceeds 320,000. In the region of the second minimum the dependence on molecular weight is complex. Intrinsic viscosity is proportional to molecular weight both at low and at high molecular weight and thus indicates freely draining structures. There is a conformational contraction, however, at molecular weight about 320,000 leading from one type of structure to the other. The structure at higher molecular weight may involve a specially strong bond between specifically grouped segments in the chain. The positions of the extrema along the alcohol concentration axis are not molecular weight dependent, particularly above 320,000. Results available for molecular weight dependence in methanol agree well with this picture. The present results confirm prediction inherent in the model of Silberberg and Priel and Silberberg.
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  • 48
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 747-752 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Growth rates of G of low-melting spherulites in fractions of trans-1,4-polyisoprene have been measured. The data were analyzed by use of an equation, ln G = ln G0 - ΔF*/RTc, valid at temperatures close to the equilibrium melting point. Plots of ln G against a function of the critical free energy of nucleation ΔF* result in a family of straight lines having a common intercept, ln G0, which is independent of molecular weight. The slope of these lines is a measure of the interfacial free energy of the crystallites and increases with the molecular weight, reflecting increasing irregularity in the structure of the semicrystalline mass. Comparison of growth rates of low-melting and high-melting trans-1,4-polyisoprene indicates that G0 does not, to a first approximation, depend on the nature of the crystals growing from the melt. The temperature at which spherulites of the two crystalline forms grow at equal rates has been calculated.
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  • 49
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 489-497 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A quantitative theoretical calculation is made of the effect of birefringence of the surrounding medium on the light-scattering pattern from a two-dimensional anisotropic spherulite. The calculated modification of the light-scattering pattern is in accord with the prediction previously made on the basis of qualitative considerations and model experiments.
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  • 50
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Light scattering from oriented samples of crystalline polymers is affected by the birefringence of the sample. An extension of the theory for scattering from uniaxially deformed two-dimensional and three-dimensional spherulites is made so as to include the retardation of the incident and scattered beams in passing through the birefringent sample. Strain influences scattering, in that it changes the birefringence of the sample and it also changes the anisotropy and shape of the spherulites. Scattering intensities are calculated for both crossed and parallel polarizers as a function of Ω, χ, and Φ, where Ω is the angle between the stretching direction of the sample and the horizontal direction, and χ and Φ are the angles between the stretching direction and the polarization directions of the polarizer and analyzer, respectively. It is shown that for crossed polarizers with Φ = 45° and χ = 45° birefringence changes largely influence the results but that for the polarizers parallel at Φ = 0° and χ = 0° or crossed at Φ = 90° and χ = 0° the birefringence effect is minimized. The intensity distributions for crossed polarizers at Φ = 45° and χ = 45° from polyethylene films stretched to give retardations up to several wavelengths, are found to be in good agreement with the calculated results.
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  • 51
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 529-540 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photocurrents have been detected in a wide range of simple polymer systems at irradiation wavelengths as high as 365 mμ. These photocurrents are shown to be due to phtoemission from the electrode system. Pulsed photoconductivity experiments show that at least two stages of charge transport are involved. In the first stage photoemitted electrons travel a short distance into the polymer before being trapped. This is followed by a slower process of trap-dominated charge transport.
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  • 52
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 571-581 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansion of a butadiene-styrene copolymer filled with carbon blacks differing tenfold in mean particle size (HAF and MT) was investigated. The glass transition was unaffected by MT and was raised only 0.2°C for every 10 parts per hundred by weight of polymer of HAF black added. The coefficient of expansion of the polymer component of the composite in the rubbery region was substantially unaffected by either carbon black, but decreased markedly with increasing black loading in the glassy state. These results suggest that free volume is not altered appreciably by the presence of the filler in the rubbery state, but expands with decreasing temperature below Tg. The latter effect is explained by dilatation due to stresses set up around filler particles, arising from differences in the expansion coefficients of filler and polymer, which are not relieved in the glassy state. The near invariability of Tg and of the rubbery fected by adsorption of polymer segments on the carbon black surface. A conservative rough estimate indicates that restriction of segmental motion is confined to a 30 Å layer around the particles in which Tg is elevated by only 10°C.
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  • 53
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 637-642 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 54
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1897-1908 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of molecular weight distribution on the viscoelastic properties of “entangled” polymers has been examined with blends of narrowly distributed polystyrene and broadly distributed polydimethylsiloxane. It is shown that blending laws established for nonentangled polymers do not apply to high molecular weight systems. The steady-state shear compliance of a blend is examined as a function of its molecular weight and the molecular weight of its components, and an approximation is given for the longtime viscoelastic response of entangled blends.
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  • 55
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1927-1935 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The storage (J′) and loss (J″) shear compliances have been measured for two random copolymers of styrene and n-hexyl methacrylate with styrene contents of 18% and 30% (by weight) in the frequency range 45-4400 Hz and the temperature range 31-107°C. The data at different temperatures were combined by the method of reduced variables, and the WLF coefficients were calculated from the temperature shift factors by the method of Pierson and Kovacs. The data were compared with earlier data for the two homopolymers. The thermal expansion coefficient of the fractional free volume, and the free volume at the glass transition temperature, varied monotonically with composition, but the fractional free volume at a reference temperature of 100°C appeared to pass through a maximum as a function of concentration. Comparison of isothermal plots of J′ at 100°C, plots of the relaxation spectrum at 100°C, the monomer friction coefficient and its temperature dependence, and isochronal plots of the storage shear moduls at 100 radians/see all show that the properties of poly(n-hexyl methacrylate) are very slightly affected by incorporation of 18% styrene and only moderately affected by 30% styrene. By contrast, comparison of styrene-butadiene rubber with 1,4-polybutadiene shows a very large effect of incorporation of 23.5% styrene. These differences may be associated with local packing relations of the comonomer residues and suggest that copolymer properties cannot be readily predicted from those of the component homopolymers.
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  • 56
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1937-1953 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been considered for some time that the presence of birefringence in an oriented polymer must affect the light-scattering behavior. Previous analyses of this phenomenon are restricted to single-particle scattering. A more complete theory of the effect of birefringence on the scattering of light from correlated systems is presented. The measured scattering intensity is shown to be dependent upon the optical properties of the sample as well as the experimental technique and conditions.
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  • 57
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1987-1997 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An experimental technique for the simultaneous measurement of solubility and diffusion coefficients in polymers by frequency response techniques has been developed. A sample of polymer suspended from an electrobalance is exposed to a permeating gas whose pressure is being varied sinusoidally at ultra-low frequencies. The phase angle and amplitude of the weight changes are measured as a function of the frequency of the pressure wave. It is shown that in the linear range the diffusivity coefficient for polyethylene-ethane calculated from the phase angle lag and the Henry's law solubility and the diffusivity obtained from the amplitude ratios are in excellent internal agreement and also agree with values obtained from transient measurements.
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  • 58
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1999-2014 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper describes the use of a new air-bearing torsion pendulum as a nondestructive monitor of torsional fatigue in epoxy resin castings. Results indicate that both G′ and tan δ undergo significant changes as fatigue is induced in the specimen. In those specimens that have not been sufficiently post-cured, cyclic fatiguing induces further crosslinking. However, this is accompanied by a competing reaction of crack formation and propagation leading ultimately to failure.
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  • 59
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2033-2034 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 60
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 969-977 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic wide-line proton magnetic resonance absorption spectra of a number of representative cellulose preparations have been obtained in the dry state and after addition of about 7% water. Line widths, second moments, spin-spin and spin-lattice relaxation times have been determined. The second moment of the absorption curve of dry cellulose was found to correlate well with the crystalline fraction for most specimens. A technique is described for determining the number of water-cellulose protons exchanging relative to the number of cellulose protons not exchanging. The reduction in absorption line width observed when water is added to cellulose is shown to be quantitatively consistent with such a proton exchange phenomenon.
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  • 61
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2029-2032 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 62
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2035-2035 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 63
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2067-2078 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An elastic-fluid theory of die-swell for long dies is presented. The theory predicts a swelling ratio De/d asymptotically proportional, for large values of swelling, to the cube root of the recoverable shear evaluated at the die wall. Here the recoverable shear is defined to be half the ratio (first normal stress difference/shear stress). Excellent agreement is shown between predicted De/d and measured De/d for experiments on melts and solutions for which adequate data are available.
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  • 64
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2051-2065 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR relaxation times T1 and T2 have been measured for fractionated samples of polydimethylsiloxane with different molecular weights in the amorphous state and in tetrachloroethylene solutions. The results are interpreted on the basis of the anisotropic reorientation model proposed by Woessner for small molecules. A correlation time characteristic of the diffusional rotation of chain segments is calculated and shown to be proportional to the square root of the bulk viscosity.
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  • 65
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2039-2050 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Fujita equation relating molecular weight distribution to concentration of solution subjected to centrifugal forces in equilibrium proved to be an improperly posed problem in the Hadamard sense. Application of Tikhonov's regularizing functions leads to a good approximate solution of Fujita's equation. Such functions have been applied to a monomodal and a bimodal molecular weight distribution, and approximate results have been computed.
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  • 66
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1089-1110 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gelation of poly(methacrylic acid) in water was studied as a function of degree of neutralization with NaOH. It was found that charging the molecular displaces the onset of gelation to higher concentrations but makes the transition occur over an even narrower concentration range. This extreme sensitivity of rheological properties to charge may play a role in biocolloidal systems. The phenomenon of reversible gelation is discussed in general and related to the properties of the particular system. The method of measurement, which involves the determination of the dynamic response in the 1 Hz region and the measurement of phase angle, is described in detail. A method of deriving the relaxation time spectrum from measurements of phase angle is given.
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  • 67
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1111-1126 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Comonomer and stereosequence distributions in linear high polymers are considered from the point of view of the general theory of stationary random sequences. Although the discussion is centered about binary polymerizations which may be regarded as stationary Markov processes of low order, attention is paid to distinguish results valid for any stationary random process including stationary non-Markov processes from those special to a particular Markov process. Alternative derivations of copolymer composition equations are given along with a corrected version of a previously suggested scheme of relating conditional probabilities of different orders. The nature and relative merits of the several measures proposed in the literature to characterize comonomer and stereosequence distributions are also discussed in some detail.
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  • 68
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1127-1136 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory for scattering of light from films in which the orientation correlation between two scattering elements depends upon the angle β between the optic axes and the vector connecting the two elements is extended. A delta-function type dependence is assumed in which the correlation is strongest when β equals some preferred value β0. Calculated results of scattered intensities are shown to be similar to experimental observations.
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  • 69
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1169-1175 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly-4,4′-oxydiphenylenesulfonyl and poly-4,4′-methylenediphenylenesulfonyl were synthesized by an electrophilic substitution polymerization of the arylene monosulfonyl chloride monomers. The glass-transition temperatures Tg of these polymers were determined by calorimetric and dynamic mechanical measurements, and the number-average molecular weights were determined by vapor-pressure osmometry. Both polymers were found to have the same Tg at equivalent molecular weight; the limiting value at high molecular weight is 238°C. Both polymers have two dynamic mechanical relaxation peaks at temperatures far below Tg. One is in the neighborhood of 0°C, and the other is at -110°C. Plausible origins for these relaxations, and the absence of any near 0°C in poly(4,4′-isopropylidenediphenylene-co-4,4′-sulfonyldiphenylene dioxide), are discussed.
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  • 70
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1211-1225 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To determine the true reason for the increase in birefringence and the decrease in relaxation modulus for high-density polyethylene with rising temperature, changes in crystalline structure as well as in thermal, viscoelastic, and rheo-optical properties with temperature were measured, by several techniques, including DSC, DLI, infrared dichroism, x-ray diffraction, and NMR. The values for degree of crystallinity obtained from the DSC fusion curve, density, and infrared absorbances coincide very well and show almost no divergence till about 80°C. The optical vertical shift factor pT can be related to the ratio of the orientation function for the crystal c axis at an arbitrary temperature to that at the references temperature, fε/fε0. The mechanical vertical shift factor bT, on the other hand, is associated with the temperature dependence of the mobile fraction, as determined by NMR measurements, but not with variations in degree of crystallinity.
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  • 71
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1291-1302 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Changes produced in γ-irradiated polyethylene by subsequent ultraviolet irradiation have been investigated by ESR measurements, ultraviolet spectroscopy, and viscometric determination of average molecular weight. The photoinduced changes depend on the wavelength of irradiation. Upon irradiation at wave length greater than 3900 Å, main-chain scission occurs by reaction of trapped allylic radicals: A reduction in molecular weight sndicated by this reaction was verified by fractionation experiments and molecular weight determinations.
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  • 72
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1279-1289 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Selenacyclobutane (trimethylene selenide) readily undergoes photochemical reaction to give polymeric products. Also, the material polymerizes rapidly when the polycrystalline solid film liquifies on a salt substrate in vacuum. Upon polymerization of the sample, infrared and Raman spectra exhibit profound changes which definitely establish ring cleavage. The Raman spectra of the polymer reveal strong C-Se stretching peaks but little or no scattering in the region of Se-Se stretching, strongly suggesting that the polymerization process proceeds in a regular head-to-tail fashion. An EPR study of the monomer exposed to ultraviolet radiation at -180°C supports this fact, since the resulting spectrum is indicative of an intermediate radical species, (CH2CH2-CH2Se)n., where n is sufficiently large that the terminal electrons do not interact. No triplet spectra were observed. Molecular oxygen apparently plays an important role in the polymerization kinetics, since it is found that degassed samples of the substance, in contrast to those which have not been degassed, polymerize rapidly even under room illumination. Freezing-point depression measurements fix a lower limit to the average molecular weight of the polymer at 2700 (n = 23 monomer units).
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  • 73
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is shown that the Hirai-Eyring model for the liquid state is capable of accurately describing the p, V, T behavior of liquid polymers in the temperature range over which measurements are now made, and below. Once the parameter choices necessary to accomplish the fit are made for a particular polymer, the excess thermodynamic functions (differences in properties, liquid less solid) are determined by the same parameters. Above the glass transition temperature Tg the volume, excess enthalpy, and square of the excess entropy are predicted by the model to be essentially linear with temperature, in agreement with experiment. Below Tg, these functions do not remain linear (as is usually assumed in extrapolating the equilibrium behavior to low temperatures), but instead they rapidly approach zero in a continuous way as the temperature is lowered. These remarks apply to glass-forming materials composed of small molecules, as well as to polymers. The “paradox” raised by Kauzmann is thus resolved, and the Gibbs-DiMarzio second-order transition appears to be unnecessary.
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  • 74
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of long-and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed. The calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept and previously established relationships for the effect of branching on molecular dimensions. Typical calibration curves are shown for different branching models and degrees of branching. As branching increases, the curves are shown to converge. Methods of characterizing branching and molecular weight distributions of franctions and whole polymers from GPC and intrinsic viscosity data are presented.
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  • 75
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The recently developed methods of characterizing branching in polymers from gelpermeation chromatography and intrinsic viscosity data are verified experimentally. An iterative computer program was written to calculate the degree of branching in whole polymers. Long-chain branching in several low-density polyethylene samples was determined by both the fraction and whole polymer methods. The two methods gave consistent ranking of the branching in the samples although absolute branching indices differed. Effects of various experimental errors and the particular model used for branching were investigated. For polyethylene, the data show that the effect of branching on intrinsic viscosity is best described by the relation 〈g3〉W1/2 = [η]br/[η]1 where 〈g3〉w is the weight-average ratio of mean-square molecular radii of gyration of linear and trifunctionally branched polymers of the same weight-average molecular weight.
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  • 76
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1323-1336 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular orientation in poly(ethylene terephthalate) (PET) fibers was studied by polarized fluorescence. The observed amorphous orientation of the spun as fiber was not random but uniaxial along the fiber axis. This orientation increased with draw ratio up to about 2 and then remained fairly constant. The amorphous regions of PET fibers were disoriented when the fibers were heated while unconstrained. The fluorescence data obtained were correlated with shrinkage measurements. Fluorescence data indicated that spin drawing had more effect upon orientation than subsequent drawing of the fiber, whereas birefringence data indicated the opposite. The reason for this behavior is discussed.
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  • 77
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1387-1393 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(ethylene adipate), poly(ethylene suberate), and poly(ethylene sebacate) were synthesized by a modified ester interchange procedure. Polydispersity was reduced and low molecular weight material removed by fractional crystallization. Samples of 50-60% crystallinity were prepared by bulk crystallization and annealing. Melting points and amorphous densities were obtained by dilatometry. Melting points were 7-12°C higher than previously reported. Heats of fusion were measured by differential scanning calorimetry and extrapolated to 100% crystallinity by using measured amorphous densities and recently redetermined crystalline densities. Entropies of fusion were calculated and separated for the first time into volume expansion and conformational contributions.
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  • 78
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1503-1519 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A statistical theory for the scattering of light from oriented polymer films is developed in terms of angularly dependent generalized correlation functions. Numerical calculations of scattering patterns are carried out for special cases. The scattering depends upon two types of distributions describing (1) the orientation distribution of optical axes of scattering elements and (2) the angular dependence of correlation in orientation between pairs of optic axes. These distributions are expanded in Fourier series (in a two-dimensional treatment), the coefficients of which are functions of elongation and describe the elongation dependence of the scattering patterns.
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  • 79
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1545-1564 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization of compression-molded isotactic polypropylene and polyethylene is invariably spherulitic; generally, nucleation occurs randomly throughout the sample. In a special case where nucleation predominates at the surface, spherulitic growth centers become crowded and are forced to propagate unidirectionally into the bulk (transcrystallinity). Conditions for the formation of transcrystallinity have been investigated by optical and scanning electron microscopy. The occurrence of transcrystallinity is attributed to heterogeneous nucleation induced at the mold surface. To be effective, the mold surface must have a nucleating efficiency equal to or greater than that of adventitious nuclei present in the polymer. As the crystallization temperature approaches the melting point, the activity of mold surfaces is found to increase leading invariably to transcrystalline formation. The degree of activity of various mold surfaces correlates with the known activity of specific dispersed nucleating agents having similar chemical structures. Contrary to claims in the literature, the surface energy of the mold surface and temperature gradients across the melt surface do not play a primary role in transcrystalline formation of polypropylene.
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  • 80
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1585-1597 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to study the dielectric behavior of polyoxymethylene prepared by radiation-induced solid-state polymerization, large crystals of tetraoxymethylene (2 cm in diameter) were prepared by Bridgman's method and polymerized by γ-rays. The x-ray diffraction pattern of the polymer did not reveal the existence of a so-called amorphous region. In dielectric measurements, only one dielectric absorption was observed in the low-temperature region, while in the high-temperature region ε″ did not change up to about 120°C, where thermal decomposition started. When the specimen was stabilized by acetylating the endgroups in the solid state, ε″ did not change up to about 150°C. This dielectric absorption showed a significant anisotropy for the direction of an applied field. The dielectric absorption was much larger when the electric field was perpendicular to the fiber axis than when the field was parallel. The dielectric absorption was larger in a specimen which was estimated to be more imperfect according to DSC analysis. This leads to the conclusion that the dielectric absorption is attributable to defect regions. On the other hand, the dielectric absorption became larger with increasing numbers of terminal OH groups, and hence it is attributable to the response of the terminal OH groups. Moreover, the dielectric absorption was depressed by the acetylation of the OH groups in the solid state. It is, therefore, concluded that the dielectric absorption observed in polyoxymethylene prepared by solid-state polymerization of tetraoxymethylene is due to the response of terminal OH groups localized in defect regions. Polyoxymethylene crystallized from the melt gives an asymmetric low-temperature absorption. This asymmetry can be ascribed to the superposition of two relaxation processes. When its absorption curve is compared with that of the solid-state polymerized polymer, the low-temperature component can be assigned to crystal defects and the high temperature one to amorphous regions.
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  • 81
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1627-1634 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Superposition of the loss tangent curves could be achieved for the β-transition of a series of homologous epoxy resins. It was found that both a vertical and horizontal shift were necessary to achieve superposition when the curves were plotted as the logarithm of the loss tangent versus reciprocal absolute temperature. Resins from the diglycidyl ether of bisphenol A (DGEBA) were prepared with five different curing agents and their loss tangent curves measured on a free-oscillation torsion pendulum (ca. 1 cps). The β transition is caused by DGEBA, which was found via molecular models to contain a mobile group. The intensity of the loss for three of the resins was found to be proportional to the concentration of DGEBA, molecular models revealing that no additional mobile groups were introduced by these curatives. The remaining two curing agents introduced mobile groups into their systems and for these two, no separate transitions were identified but the intensity of the DGEBA β transition was increased. This may be caused by a coupling of the DGEBA mobile groups through the flexibility of the curative-introduced mobile groups.
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1637-1637 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 83
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1651-1659 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is pointed out that a theory proposed by Vrij for the expansion of a linear polymer chain in solution beyond its unperturbed size is also applicable formally to branched chains. The theory predicts the temperature at which the chain obeys random-flight statistics to be lower for a branched chain than for a linear one (for a polymer-solvent system exhibiting the usual upper critical consolute point). Vrij's derivation follows a well-known procedure of Flory, but refines it to take account of the variation of the time-averaged segment density with distance from the center of mass of the chain. This modification in combination with a somewhat different derivation is shown to lead to a similar result. Yet another scheme for “correcting” Flory's theory is outlined. Some reasons are advanced for questioning the physical significance of these small modifications of Flory's theory, all of which depend on the retention of previously ignored terms in power series expansions.
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  • 84
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 595-603 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption of tritium-labeled sodium stearate and 35S-labeled sodium dodecylsulfate from aqueous solution on bent and on stretched polyethylene strips was directly measured. The amount of adsorption increased from 2.5 to 4.5 times on surfaces of various polyethylene samples stretched from 5.2 to 5.3 times the original length. For one sample, adsorption increased 8 and 2.5 times, respectively, on the convex and concave surfaces of a bent strip. Autoradiographs of the strips taken after adsorption revealed the appearance of both homogeneous and heterogeneous adsorption on the stretched surface of the polyethylene. The electron micrographs of the strips showed that many small fissures, about 1-5μ in length, formed on their surfaces after the strips were bent or stretched. Enhanced adsorption of the surface-active substance along these fissures was suggested. On the basis of these observations, it is proposed that in stretching or bending, fissures increase adsorption of the detergent, and the adsorption in turn promotes further development of fissures. Thus, bending and adsorption mutually promote the growth of fissures which finally result in failure of the polyethylene.
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  • 85
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1-17 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An apparatus is described and a method discussed for determining the rheological characteristics of elastic liquids during extension at constant rates of deformation and extension. The material studied was polyisobutylene of molecular weight 7 × 104. At low constant deformation rates steady-flow regimes were achieved, with corresponding equilibrium high elastic strains. A detailed study has been made of the process of attainment of steady-flow regimes and it is shown that before steady flow is reached the curve of longitudinal viscosity versus strain passes through a maximum. As the rate of deformation rises, the strains at which steady-state flow regimes are achieved increase, and the time required to reach these regimes decreases. Qualitatively this occurs in the same way as upon shear. The dependence of equilibrium high-elastic strains (under steady-flow regimes) on the rate of deformation has been determined. At steady-flow regimes the stress depends linearly on the rate of deformation at low values of the stress. Under such conditions Trouton's formula is valid. At constant rates of extension the stress versus time curve passes through a maximum which becomes higher with increasing extension rates.
    Additional Material: 10 Ill.
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  • 86
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 47-59 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple method of preparing thin uniform films of high polymers has been examined for growing single crystals from solution. Single crystals of polyethylene, polypropylene, polybutene-1, polyacrylonitrile, and cellulose triacetate have been obtained by this method. Different stages of growth reveal different growth features that are also obtained from solutions of these polymers by changing temperature and concentration.
    Additional Material: 19 Ill.
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  • 87
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 35-45 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method for the determination of the molecular weight spread in the narrow peaks in the GPC chromatograms of nitric acid-degraded polyethylene is presented. It is found that polar endgroups added to the polymer chains during scission cause the peaks to be broader than those of paraffins with the same molecular weight spread. After allowing for this extra instrumental broadening, estimates are made of the molecular weight spread for unannealed and annealed single crystals of polyethylene and bulk polyethylene as a function of degradation time. It is proposed that after long degradation times the molecular weight spread is a measure of fluctuations in the original crystalline lamellar thickness.
    Additional Material: 1 Ill.
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  • 88
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 61-70 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The real and imaginary components of the complex piezoelectric strain constant, which relates the polarization to the applied stress, have been determined for elongated films of poly(γ-methyl L-glutamate) over the temperature range -170°C to +170°C at a frequency of 20 Hz. The variation of the piezoelectric constant with temperature is similar for both α-helical and β-form molecular conformations. The sign of piezoelectric polarization is opposite for L and D polymers. A simple model, representing the piezoelectric crystallites as embedded in nonpiezoelectric amorphous regions, is proposed to account for the piezoelectric temperature dispersion curves.
    Additional Material: 9 Ill.
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  • 89
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 81-87 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The high degree of flexibility of blends containing minor amounts of partly crystalline copolymers of ethylene and vinyl acetate in paraffin wax seems to be a manifestation of some type of interaction. Low-angle x-ray diffraction of such blends showed a new long spacing intermediate in length between the polymer long spacing and the c axis length of the wax unit cell. This new long spacing appears to be a consequence of isomorphism involving cocrystallization of polymeric ethylene sequences and wax molecules. A lesser type of isomorphic interaction, epitaxy, occurs in polyethylene-wax blends: wax overgrows crystals of already crystallized polyethylene in the same orientation without a change in its c axial dimension.
    Additional Material: 2 Ill.
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  • 90
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 89-103 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theoretical justification for using M[η], or a similar quantity, as a universal calibration parameter in GPC is reviewed. The equation based on this parameter is applied to transform the primary calibration curve, obtained by means of polystyrene samples, into calibration curves for poly-α-methylstyrene, polypropylene, and linear polyethylene. The Mark-Houwink equations for these polymers, as they are used in the transformation, are discussed. The resulting GPC calibration curves are compared with molecular weights and peak elution volumes of fractionated poly-α-methylstyrene and polypropylene. The same comparison is made with samples of polypropylene and polyethylene having very broad molecular weight distributions. The agreement lies within experimental error.
    Additional Material: 3 Ill.
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  • 91
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption of several toluene-soluble polymers at the toluene-water interface has been investigated by using the duNouy ring method of measuring interfacial tension γT/W. Polystyrene and poly(ethylene-co-vinyl acetate) (11.1 mole-% vinyl acetate) have little affinity for this interface at 29°C, but poly(methyl methacrylate) (PMMA) (M̄n = 420,000) and ethyl cellulose (EC) (M̄n = 50,100; 49.1% ethoxyl) adsorb significantly at concentrations as low as 1.0 × 10-4 g/100ml. A plot of interfacial tension lowering versus initial logarithm of initial bulk phase polymer concentration is linear from 1.0 × 10-4 to 1.0 × 10-1 g/100 ml for EC and 1.0 × 10-4 to 1.0 × 10-2 g/100 ml for PMMA. When the PMMA concentration increases to 1.15 × 10-1 g/100 ml, its adsorption behavior changes markedly. Prolonged time effects occur and adsorption becomes dependent upon dissolved water content of the toluene prior to formation of the toluene/water interface. Such effects are not observed with the other solutions studied. Increasing temperatures have variable effects on values of γT/W for the polymer solutions studied. Experiments with various polymer mixtures indicate that the polymer lowering T/W the most is preferentially adsorbed at the toluene-water interface and rapidly displaces less strongly adsorbed polymers.
    Additional Material: 4 Ill.
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  • 92
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 143-147 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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  • 93
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 869-882 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization kinetics of a high molecular weight fraction of linear polyethylene was studied in dilute solutions of p-xylene, n-hexadecane, and decalin by dilatometric methods. For all solvents and temperatures, the experimental isotherms could be quantitatively described by the Avrami formulation for the complete transformation. This result is unique in the realm of polymer crystallization, since marked deviations from this theory are usually observed in more concentrated systems. The Avrami exponent is found to be n = 4 in all cases. The temperature coefficients of the rate constants are indicative of a nucleation controlled process. The data fit either a two-dimensional or three-dimensional nucleation mode, and a discrimination can not be made between these two cases. The interfacial free energies are found to be independent of the solvent medium. It is also shown that, irrespective of the type of nucleation control governing the kinetics, the same type governs the crystallite thickness of the lamella-like crystals that are formed.
    Additional Material: 8 Ill.
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  • 94
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1027-1037 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly-2,5-distyrylpyrazine (poly-DSP) was investigated by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and measurements of dynamic viscoelastic and electrical properties. From DTA and TGA studies it was confirmed that poly-DSP melts at 321°C and depolymerizes rapidly to the monomer at temperatures between 335°C and 345°C in helium. The polymer is affected by oxygen above 200°C. The E′ value from dynamic viscoelasticity measurements on amorphous film is 2 × 1011 dyne/cm2 at room temperature. It decrease abruptly in the temperature range 140-150°C; but the net decrease of E′ within this temperature range is relatively small. The electrical properties of amorphous poly-DSP are characterized by a small temperature dependence of the dielectric constant between room temperature and 100°C. The dielectric loss tangent was observed to be small, and the dc conductivity was extremely small. It is concluded that rotation of the phenyl branches in the polymer occurs above -30°C and the glass transition occurs at about 150°C. These properties are discussed in some detail in relation to the polymer structure.
    Additional Material: 11 Ill.
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  • 95
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1137-1157 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scattering of light by a two-dimensional spherulite of radius R is calculated when there is disorder of optic axis orientation with respect to the radius. Special cases are considered when (1) the disorder occurs in the radial direction only, (2) the disorder occurs in the angular direction only, (3) there is combined radial and angular disorder, and (4) the optic axis makes a constant angle with the radius but there is disorder in the twist angle about the axis. In all of these calculations, a correlation function for disorder is defined and the scattering pattern depends on the ratio of the associated correlation distance to the size of the spherulite. With decreasing correlation distance, the azimuthal dependence of the scattering becomes less and there is a change in the variation of scattered intensity with scattering angles in a manner dependent upon the type of disorder.
    Additional Material: 6 Ill.
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  • 96
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1177-1186 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The loss peak caused by molecular motion of the molecules in crystalline regions appears at about 70°C (110 Hz) (α1 absorption) for the α form, and at about 110°C (110 Hz) (α2 absorption) for the β form. Orientation significantly affects the magnitude of the β absorption which appears at about -40°C. The very high value of the dielectric constant for stretched film is believed to be due to the orientation effect. The γ absorption, which is assumed to be local-mode absorption, is not so much affected by orientation. An additional loss peak has been found at around 0°C in dynamic mechanical measurements, but the molecular mechanism is unknown.
    Additional Material: 6 Ill.
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  • 97
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1395-1409 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational contribution to the entropy of fusion was calculated for poly(ethylene adipate), poly(ethylene suberate), and poly(ethylene sebacate) from consideration of rotational potentials and steric interactions in model systems. An enumeration scheme similar to that applied to polyethylene was used. Comparison of the observed and calculated conformational entropies indicated the importance of a high-energy chain twist in the crystalline polyesters in reducing their measured conformational entropies. The rigidity of the polyester chains in the melt is discussed in comparison to polyethylene. The contribution of the polar ester groups to the heats of fusion of the polyesters is evaluated semiempirically.
    Additional Material: 6 Ill.
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  • 98
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 417-436 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A technique for estimating Mc, the molecular weight between crosslinks, of amine-cured epoxy resins is described. The technique is based upon the stoichiometry of the curing reaction and the amount of primary amino and epoxy groups remaining in the polymer at a given time. The Mc values so calculated are shown to be consistent with Mc results obtained from separate measurements of swelling and the polymer-solvent interaction parameter χ1 for the range of polymer concentration in which both measurements could be obtained. A means of estimating the relative reaction rates of the primary and secondary amino groups with the epoxy groups is given. Under proper curing conditions the amine-epoxy reaction goes very nearly to completion. The presence or absence of an exotherm has no noticeable effect on the course of the reaction between bisphenol A-epichlorohydrin (Epon 828) and methylene dianiline.
    Additional Material: 5 Ill.
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  • 99
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 437-445 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of a series of epoxy polymers of known network structure have been investigated. It was shown that the distance between crosslinks could be predicted from either the shift in the glass transition temperature Tg or by use of the dynamic modulus above Tg. The front factor in the equation of state for rubber elasticity was near unity for stoichiometric equivalence of epoxy and amine and increased slowly with excess of either component.
    Additional Material: 4 Ill.
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  • 100
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 447-453 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two types of (KPO3)n crystals have been obtained: transparent crystals and semitransparent crystals that grew in the neighborhood of the wall of the crucible. In the latter type of crystals, four kinds of radicals, denoted B, C, D, and E, are observed by ESR measurements at 77°K on crystals irradiated with γ-rays at the same temperature. The probable structure of B, C, and D radicals is concluded to be —O—PO̊2—O— from their g values and hyperfine constants (the superscript circle indicates a hole trapped in the radical). When these crystals are heated to room temperature, the ESR spectra of B, C, and D radicals disappear and the spectrum of another radical appears. This radical, designated A, has the possible structure —O—ṖO2. The assumption that B radicals thermally decompose into A radicals is confirmed by experiment. With the transparent crystals, C, D, and E radicals are observed at low temperature, but only E radicals are stable at room temperature. The structure of the E radical is thought to be\documentclass{article}\pagestyle{empty}\begin{document}${\rm \hbox{---}O \hbox{---}PO}_2{{_\circ} \atop ^{\hbox{---}}} {\rm PO}_2 {\rm \hbox{---}O\hbox{---}} $\end{document}, but more detailed studies are required.
    Additional Material: 4 Ill.
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